1. Field of the Invention
This invention relates to a sensing device, especially to a sensing device for detecting material depth, liquid-level, and temperature.
2. Description of Related Art
A sensing device for detecting material depth and liquid-level is very important. The sensing device can be applied to petrochemical industry, food industry, feed industry, steel industry, cement industry, etc. The sensing device is to detect a storage amount of material in a warehouse for a monitoring purpose.
The conventional sensing device only can detect either material depth or liquid-level. The material or the liquid such as gasoline, coalmine, iron sands, cement, corns, wheat, wheat flour, or liquid can be detected. There are multiple thermal sensors installed in the sensing device for detecting material depth or liquid-level, so the sensing device can respectively monitor the material depth and temperature, or the liquid-level and temperature. The liquid-level can be detected through different approaches as follows.
1. The sensing device uses an impulse voltage to generate a magnetic field variation for detecting the liquid-level.
2. The sensing device measures an electric conductivity of liquid to obtain the liquid-level.
3. The sensing device measures variations of liquid tension and impedance to calculate the liquid-level.
The liquid-level sensing device as stated above cannot measure solid because a probe of the sensing device is easily broken by impact and the liquid-level is calculated based on a physical vibration of the liquid. When the material in the warehouse is changed, the sensing device needs to be promptly changed to accommodate the new material for monitoring.
According to the issue as above, how to obtain information of temperature, material depth, and liquid level by the same sensing device needs to be further explored.